import java.util.ArrayList;
import java.util.HashMap;

public class Collection_{
    @SuppressWarnings({"all"})
    public static void main(String[] args) {
        ArrayList arraylist = new ArrayList();
        arraylist.add("jack");
        arraylist.add("tom");
        HashMap hashmap = new HashMap();
        hashmap.put("np1","北京");
        hashmap.put("n02", "上海");
    }
} 